Relationship between structure and viscosity of CaO-SiO2-Al2O3-MgO-TiO2 slag

Structure of the CaO-SiO2-Al2O3-MgO-TiO2 slag was studied by molecular dynamics simulation at 1773 K. Additionally, part of viscosities were measured for quantitatively establishing the relationship between the structure and viscosity with varying basicities and TiO2 additions. Role of TiO2 as basic oxide was verified and it can be inferred that the structure of TiO2 is relatively similar to MgO compared to CaO. In addition, distribution of three different types of O was presented from which it can be obtained that nonbridging oxygen preferentially localized beside Si rather than Al. Moreover, parameter alpha(M) was proposed to estimate charge-balancing capability of M for [AlO4] (where M denotes Ca2+, Mg2+, Ti4+) along with the average values of alpha(Ca), alpha(Mg) and alpha(Ti) equaling to 1.731, 1.282 and 1.092, respectively, suggesting that Ca2+ is preferentially compensated for [AlO4] than Mg2+ and Ti4+. Therefore, TiO2 and MgO have a prominent effect on depolymerizing the framework of the slags than CaO in slags containing high Al2O3. Finally, the natural logarithm of the measured viscosities exhibit a linear dependence on the fraction of Q(4) for Si, indicating that the degree of polymerization for Si is still the principal factor which affects the viscosity despite the complicated composition. (C) 2014 Elsevier B.V. All rights reserved.